A building refers any kind of architectural structure. Depending on how they are used, buildings can be classified into various kinds, such as residential buildings, office buildings, factory buildings, performing art buildings.
Such conventional buildings are designed such that rooms that residents are allowed to use are distinctly defined.
However, when rooms that each resident is allowed to use are defined in this way, there is a possibility there is a room in which residents may rarely use (for example, residents may not even use the room for an extended period like a day, week, month, etc.). Accordingly, the utilization rate of the room drops sharply, which may be inefficient in use in terms of the overall rooms.
Specifically, as the general public are increasing their standard of living, more people are demanding rooms for a specific use (for example, a home theater, a luxury bathroom, a working room, etc.), and moreover, people are reluctant to share rooms with others. For this reason, economically, only the wealthy have been able to possess such rooms.